This proposal puts forth a series of synthetic and physical-organic studies aimed at developing three classes of thermally-stable signal amplification reagents for use in point-of-care diagnostics. The reagents will enable trace-level detection of markers of disease and pollution in assays that are inexpensive and straightforward to conduct in resource-limited environments (such as the developing world, in homes for home healthcare, and in emergency situations). The reagents are based on the hypothesis that autocatalytic and auto inductive reactions will be particularly effective at amplifying signal for detection event. The focus of the proposal is on the design, synthesis, and physical organic studies of these reagents in an effort to optimize their performance for diagnostic assays. This optimization effort includes enabling 5000 signal amplification within a 1 h assay, providing unambiguous colorimetric readouts, and ensuring that background signal that could lead to false positive results is eliminated. The performance of the reagents will be tested in the context of assays for water quality (fluoride will be the analyte), the purity of drugs (palladium will be the analyte), and for detecting influenza neuraminidase at levels that correspond to the first 24-48 h of an infection.